A product using a spray can, such as a dust blower, for example, is manufactured by filling a metallic spray can having a spray button with a propellant such as a compressed gas or a liquefied gas, etc. and dust attached to various kinds of appliances is removed by blowing off the same with gas sprayed by pushing the spray button. Conventionally, fluorocarbons have been used as the propellant for the spray products inclusive of the dust blowers, but fluorocarbons are substances causing the depletion of the ozone layer, which results in that controls on usage of fluorocarbons become severe. Under these circumstances, a propellant exhibiting a smaller ozone-depleting potential has been developed, and now, alternatives to fluorocarbons, such as HFC 134a (CH2F—CF3) and HFC 152a (CH3—CHF2) have been widely used.
However, HFC 134a is a non-flammable gas so as not to cause burning, but exhibits a global warming potential as high as 1300. HFC 152a (CH3—CHF2) exhibits a global warming potential as small as 140, but is a flammable gas so that it must be handled with care. In addition, these alternatives to fluorocarbons are expensive, and since they are fluorides, they exhibit properties of generating a highly poisonous hydrofluoric acid when contacting an open fire, which causes a serious security problem.
On the other hand, In recent years, protection of the global environment has become of major interest, and, not only the depletion of the ozone layer but also effects of such fluorocarbons on the environmental contamination, in particular, the global warming, which is caused by the emission of components of the propellant into the air, become problems which cannot be by-passed. According to Law on Promoting Green Purchasing (Law Concerning the Promotion of Procurement of Eco-Friendly Goods and Services by the State and Other Entities), products which do not cause a large environmental impact due to emission of green house gas, etc. as a result of the use thereof is defined as the “eco-friendly goods”, and with respect to the dust blower, the “evaluation criteria” thereof has been changed to “Does not use material that would damage the ozone layer, or hydro-fluorocarbon (so-called CFC alternative)” on Apr. 1, 2008.
As a result of this change, products using CFC alternatives become not “eco-friendly goods” which are goods according to Law on Promoting Green Purchasing, and consequently, dimethyl ether (DME) which does not cause the depletion of the ozone layer and exhibits a very small global warming potential, has been noted as the propellant satisfying the changed “evaluation criteria”. But, dimethyl ether (DME) is a flammable gas so as to exhibit problems in safety during using or storing of the products.
And cylinders for use in the torch burners used in various works with flames are normally cartridge-type gas cylinders manufactured by filling spray can-shaped metallic pressure-resistant containers, each having an ejection opening, with fuel such as a flammable gas, a liquefied fuel gas, etc., and the fuel is introduced into a burner attached to the ejection opening to be burnt. The above-described dimethyl ether (DME) and a liquefied petroleum gas (LPG) exhibiting a high calorific value, emitting only a small amount of CO2 in a combustion exhaust gas, as compared with petroleum oil and coal, and causing no depletion of the ozone layer, have been used as the fuel for the torch burner.
The cylinder for a torch burner has a construction similar to that of the dust blower, and uses a flammable gas so that the improvement of the safety is a very important problem. In particular, the spray can product using a liquefied gas, normally has an absorbing body manufactured by filling an interior of a spray can with fibers obtained by pulverizing waste paper, etc. Where the spray can product is used in an inverted position or a tilted position, the liquefied gas may leak from the ejection opening thereof in a liquid phase, and may catch fire.
In order to overcome this problem, the present inventors have proposed in Patent Document 1 to combine dimethyl ether (DME) with carbon dioxide as another component, thereby imparting flame retardant properties to the propellant of the dust blower. Dimethyl ether (DME) is a flammable gas, but both the ozone-depleting potential and the global warming potential are very small, and by mixing carbon dioxide gas thereinto, the safety thereof is improved.
Patent Document 1: Japanese Unexamined Patent Application Publication No. 2005-206723.
And the present inventors have proposed in Patent Document 2 an absorbing body for a spray can, which is composed of a cellulose fiber assembly obtained by pulverizing wood pulp, etc., and contains at least a prescribed amount of fine cellulose fibers having a fiber length of 0.35 mm or less. This absorbing body contains fine fibers obtained by pulverizing cellulose fibers with mechanical or chemical means, and is excellent in absorbing performance and liquid retention.
Patent document 2: Publication of unexamined Patent Application No. 2008-180377
As is disclosed in Patent document 3 through Patent document 5, a porous synthetic resin foam is known as another absorbing body. For example, in Patent documents 3 and 4, urethane resin foam is used, and a raw material is poured in an interior of a spray can and is foamed therein to make the filling process simple. And in Patent document 5, phenol resin foam is used, and after the phenol resin foam is molded to conform to the shape of a spray can, and it is pushed therein.
Patent document 3: JP Patent No. 2824241
Patent document 4: Publication of unexamined Patent Application No. Hei10-89598
Patent document 5: Publication of unexamined Patent Application No. Hei09-4797